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These hollow TiO2 nanospheres show promise in killing drug-resistant bacteria.

In the search for new ways to attack microbes, some researchers have turned to nanoparticles. Owing to their small sizes and large relative surface areas, nanoparticles make intimate contact with cell walls, where they can mediate chemical reactions that interfere with cellular function. For example, under ultraviolet light, titanium dioxide nanoparticles can generate hydroxyl radicals and other reactive oxygen species that destructively oxidize membrane lipids and proteins. Researchers are studying the effectiveness of such nanomaterials as bactericidal coatings for hospital surfaces and food-processing equipment.

Carol López de Dicastillo, Juan Escrig, and colleagues at the Universidad de Santiago de Chile have now developed a method for preparing hollow nanospheres of TiO2 (Beilstein J. Nanotechnol. 2019, DOI: 10.3762/bjnano.10.167).

The team prepared spherical particles of poly(vinylpyrrolidone) by electrospraying droplets of the polymer solution. They coated the droplets via atomic layer deposition with an ultrathin layer of alumina to promote adhesion and with a shell of TiO2. Finally, the researchers heated the particles in air to remove the polymer, yielding hollow particles.

At last month’s International Materials Research Congress in Cancún, Mexico, Escrig said that the materials were more effective than commercial TiO2 nanoparticles against common microbes, including drug-resistant strains of bacteria.

This is an original, low-cost approach to synthesizing novel TiO2 nanoparticles that exhibit promising antibacterial properties, says Federico Rosei of Canada’s Institut national de la recherche scientifique. “The role of the particles’ specific shape is not yet understood, but it has been shown to be relevant.”